Plasmid DNA of each mutation and M23 AQP4 were separately transfected into U-87MG glioblastoma or HEK-EBNA cell lines, and binding to AQP4 was assayed by a dual immunostaining protocol in which AQP4 was immunostained using a polyclonal Ab recognizing the intracellular AQP4 C terminus. This evidence concerns the gene AQP4 and glioblastoma.